Research on the Choice of Cooling Method for a Rare-Earth Wrought Magnesium Alloy Considering Temperature Distribution, Hardness and Microstructure

A "hardenability" experiment which contained solution treatment followed by single-side quenching and aging afterward of a cylinder specimen was carried out to research on the choice of cooling method considering temperature distribution, hardness and microstructure for a newly developed high-strength heat resistant rare-earth wrought magnesium alloy Mg-Gd-Y-Zr-Ag-Er. The results revealed that the closer the sample was to the quenching surface, the faster the temperature decreased. The largest measured temperature difference was 320 degrees C. The hardness was ranging from 76 to 86 HV in the quenched state, and 110 to 119 HV in the aged state. The various cooling rates had little effect on the hardness, the grains and precipitates of this kind of magnesium alloy, solution treatment followed by a lower cooling process like air cooling may be a better choice.